This invention relates generally to an electrostatographic printer or copier, and more particularly concerns a detoning cycle.
Current electrostatic brush detoning roll cleaners encounter the problem of having too much toner in the brush after prolonged use. A gradual accumulation of toner occurs due to incomplete detoning of the brush by the detoning roll. The brush then has to be vacuumed or replaced.
If detoning the brush is not 100% effective, the toner will gradually accumulate in the brush. When enough toner has accumulated, problems occur including the toner being emitted from the brush, the fiber tips no longer clean upon entering the cleaning nip, and the fibers are held in a bent position reducing contact with the photoreceptor. When these problems occur, the cleaning brushes require vacuuming to remove toner or brush replacement to restore acceptable performance. For example, in the Xerox 5100 machine, the cleaner brushes are vacuumed every 300K to remove toner from the brush that the detoning roll did not remove. When the Xerox 5100 machine brush has more than 30 grams of toner in the brush, toner clouding from the brush contaminates the machine.
Another problem that occurs is with small diameter (e.g. D=25 mm) brushes. The areas of the brush with large toner accumulation have more of a radial set than portions of the brush with lower toner accumulation. When a large accumulation of toner is present in the brush, the toner holds the brush down in the set condition (i.e. the toner forms a "mat" which holds the fibers down). This increased set reduces the cleaning efficiency of the brush. When the toner is removed from the brush, the fibers recover from this increased set. Problems caused by toner accumulation in the brush occur even with excellent detoning efficiencies, i.e. greater than 99.5%, due to gradual accumulation. Hence, better detoning efficiency delays the need for brush service rather than resolving the problem that leads to servicing the brush.
The following disclosures may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 5,291,259 to Weitzel et al discloses an image forming apparatus which includes a toner cleaning device for cleaning toner off an image surface. The cleaning device includes a cleaning applicator for moving magnetic particulate cleaning material past the surface to be cleaned. Particulate material is moved from a sump to the cleaning applicator by a transport positioned between them. A detoning roller is positioned to attract toner from particulate material associated with the transport. When the cleaning device is not cleaning, it has a mode of operation in which the transport and the detoning roller continue to operate to continue to detone particulate material which moves from the sump around the transport and back to the sump.
U.S. Pat. No. 4,811,046 to May discloses undesirable transient development conditions that occur during start-up and shut-down in a tri-level xerographic system when the developer biases are either actuated or de-actuated are obviated by the provision of developer apparatuses having rolls which are adapted to be rotated in a predetermined direction for preventing developer contact with the imaging surface during periods of start-up and shut-down. The developer rolls of a selected developer housing or housings can be rotated in the contact preventing direction to permit use of the tri-level system to be utilized as a single color system or for the purpose of agitating developer in only one of the housings at time to insure internal triboelectric equilibrium of the developer in that housing.